1. Technological Field
The present disclosure pertains generally to High Efficiency Video Coding (HEVC) intra-block coding, and more particularly to intra-block copying enhancements for in range-extension (RExt) in HEVC.
2. Description of Related Technology
High Efficiency Video Coding (HEVC) is a video compression standard which has succeeded H.264/MPEG-4 AVC and was jointly developed by ISO/IEC Moving Picture Experts Group (MPEG) and ITU-T Video Coding Experts Group (VCEG) in a Joint Collaborative Team on Video Coding (JCT-VC) to develop the HEVC standard. HEVC provides a number of enhancements in relation to previous standards, whereby data compression ratios can be doubled in relation to previous standards for a given level of video quality.
It should be appreciated that in HEVC coding, a coding tree unit (CTU) is up to 64×64 pixels, and is also referred to as largest coding unit (LCU). A CTU is the basic processing unit generally corresponding to a macroblock referred to in previous video standards. CTUs of a picture are divided for luma and chroma components into coding tree blocks (CTBs), which are divided into one or more coding units (CUs) arranged as a quadtree within each CTB. CUs are divided into prediction units (PUs) of either intra-picture or inter-picture prediction type. In coding a prediction residual, a CU is divided into a quadtree of transform units (TUs). TU data fields include skip_mb_flag, merge_flag, motion vector difference (mvd), cbf_luma, and so forth.
In HEVC according to JCTVC-N1005_v3, there are a number of elements regarding BVIntra, MV coding of IntraBC, and interaction of IntraBC, which are non-optimal.
High-efficiency video coding (HEVC) has utilized in-range extension (RExt) intra-block motion compensation or copying as an additional intra-coding mode. A flag on the coding-unit (CU) level signals this intra-block coping mode.
When a CU is subject to intra-block copying, the motion vector referring to the reconstructed areas in the same picture is signaled. The predicted sample values of the current CU will be the reconstructed sample values identified by the motion vector. The motion vector for intra-block coding are binarized using Ex-Golomb code and coded in context-adaptive binary arithmetic coding (CABAC) (e.g., an entropy coding mechanism) similar to MV difference coding in HEVC. However, the current use of RExt includes some redundancy.
Redundancy arises in relation to other aspects of intra-block coding, including a redundancy in By valid names.
Accordingly, a need exists for enhanced intra-block operations for RExt in HEVC. The presented technology fulfills that need and overcomes shortcomings of previous techniques.